Your going to find that most of us here closely guard our supplier information. We give enough information that you should be able to find everything though. We just do not like to give it away on a silver platter. If you do some searches and read through the threads you will find it though.
Here is a link to a recent thread where we explain to another poster why we do not discuss this information as opennly as you will see vendors discussed in other areas of lawnsite.
In that linked thread it is summed up pretty simply by comparing our vendors to john deere vx exmark. Your customer doesn't care what brand commercial mower you use, because it makes little difference in the quality of the cut. But in our industry, the brand of commercial product is exactly what sets us apart from our competitors